Upload
phillip-moore
View
216
Download
0
Tags:
Embed Size (px)
Citation preview
Where No One Has Gone Before…
E80: The Next Generation
Section 1, Team 1
Student 1, Student 2, Student 3, and Student 4
May 5, 2008
IntroductionOverall Objectives
Use various data to piece together an accurate picture of rocket flight
Model rocket flight and compare predicted values to collected data from actual rocket flight
Overall Strategy
Develop a method for reading and interpreting data retrieved
Determine the physical properties of the rocket used
Test and verify the sensors that would be used to obtain the desired data
Background: The RocketsThree rocket designs
Large, medium, and small
RockSim Simulates the
launches to give predictions
Background: The SensorsR-DAS
5 V range Onboard storage and
telemetry
Sensors IMU Temperature and
Pressure Modal vibrations
Launch ProcedureLaunch site: Lucerne Valley Dry Lake
3000 ft. elevation
Telemetry and rocket prep stations Timed deployment of parachute as backup
Extensive safety precautions Range safety officers Extreme care handling motors and other
explosives All spectators alert during launch
Immediate recovery and data access
Rocket 1: Large IMULaunched on April 19th with a G339N motor
Notable windspeed during launch (15-25 mph)
Objective: Use data from accelerometers and gyroscopes to model the rocket's flight
Did not have all calibration equations
Rocket 1: Large IMUZ accelerometer
data, integrated twice, yields an informative plot
RockSim predicts apogee at about 180 m. Small error in
calibration propagates significantly
0
20
40
60
80
100
120
140
0 4 8 12 16 20 24 28 32
Position (m)
Time (s)
Rocket 1: Large IMUTime (seconds after launch)
Rotational Event
0.5 Change from CCW to CW
5.5 Parachute deploys
7.5 Stop; continue CW
11 Change from CW to CCW
18.5 Change from CCW to CW
27 Change from CW to CCW
31.17 Impact
Rocket 2: Large Vibration
Launched on April 26th with a G339N motor
Equipped with 16 piezoelectric strain gauges: 6 selected along the rocket body
Objective is to collect data on modal vibrations experienced by the rocket during flight
Rocket 2: Large Vibration
All sensors read two large spikes Spike at ignition Spike at parachute
deployment
Spikes tend to be larger on sensors nearer the nose
Rocket 2: Large Vibration
Fourier transform does not reveal any resonant peaks
Results consistent across all sensors
Rocket 3: MediumTemperature and
PressureLaunched on April 26th with a G61W motor
Sensors on board 4 Thermistors 2 Pressure Transducers 2 Accelerometers
Flight Objective Observe temperature fluctuations during flight Determine flight profile from pressure and
acceleration readings
Rocket 3: MediumTemperature and
Pressure
Spike in fin thermistor reading at landing
Internal avionics are protected
Temperature offset between different makes of thermistors
Rocket 3: Medium Temperature and
Pressure
IMU noise can be neglected
Data does not compare well with RockSim predictions
Bad accelerometer data and calibrations
Converted pressure readings from both IMU and RDAS show an identical flight profile
Rocket 4: Small IMULaunched on April 19th with a G149 motor
Parachute fails to deploy Fatal flat spin; rocket destroyed
Objectives Cope with poor data Consider data immediately prior to rocket
destruction
Rocket 4: Small IMUSpikes caused
by significant changes to forces acting on the rocket
Substantial oscillation upon downward flight
Rocket 4: Small IMU
Strange shape of height trajectory caused by a lack of gravitational force on the R-DAS accelerometer
Reaches apogee at time and altitude consistent with RockSim prediction
RecommendationsSome calibrations curves were inaccurate or
missing
200 Hz sampling rate of R-DAS limits accuracy of vibration and acceleration analysis
Limited sensor sensitivity Pressure changes measured in discrete steps No measured vibration for most of the flight
ConclusionsDespite limitations, enough data and tools were
provided to establish a coherent picture of each flight
Learning to cope with deficient tools and bad data is worthwhile
Valuable field experience
AcknowledgementsE80 Faculty: Professors Spujt, Cardenas,
Miraghaie
E80 Proctors
Mudd Amateur Rocket Club (MARC)
ReferencesSpjut, Erik and Cardenas, Mary (2008). E80 The
Next Generation Spring 2008. Retrieved 25 Apr. 2008 from http://www.eng.hmc.edu/NewE80/.